Calculate the ph of 0.5 m naoh (strong base).
The Correct Answer and Explanation is:
To calculate the pH of a 0.5 M sodium hydroxide (NaOH) solution, we first recognize that NaOH is a strong base. This means it dissociates completely in water to release hydroxide ions (OH⁻). The dissociation can be represented by the following equation:
[ \text{NaOH} \rightarrow \text{Na}^+ + \text{OH}^- ]
In a 0.5 M NaOH solution, the concentration of hydroxide ions, [OH⁻], is also 0.5 M, since NaOH dissociates completely. To find the pH, we first need to calculate the pOH using the following formula:
[ \text{pOH} = -\log[\text{OH}^-] ]
Substituting the concentration of hydroxide ions:
[ \text{pOH} = -\log[0.5] \approx 0.301 ]
Next, we use the relationship between pH and pOH. The relationship is defined by the equation:
[ \text{pH} + \text{pOH} = 14 ]
Rearranging this formula gives us:
[ \text{pH} = 14 – \text{pOH} ]
Now, substituting the calculated pOH value:
[ \text{pH} = 14 – 0.301 \approx 13.699 ]
Thus, the pH of a 0.5 M NaOH solution is approximately 13.70.
Explanation
Understanding pH is crucial in many fields, including chemistry, biology, and environmental science. The pH scale ranges from 0 to 14, where values below 7 indicate acidity, values above 7 indicate alkalinity (basicity), and a value of 7 is neutral. The pH of a solution is a measure of the hydrogen ion concentration, and it is calculated using the formula:
[ \text{pH} = -\log[\text{H}^+] ]
However, in the case of strong bases like NaOH, we focus on the hydroxide ion concentration instead. When NaOH dissolves, it completely dissociates, producing a significant concentration of hydroxide ions. A higher concentration of OH⁻ results in a lower pOH and consequently a higher pH.
In practical applications, understanding the pH of solutions is essential for processes such as titration, chemical reactions, and maintaining biological systems. For example, maintaining appropriate pH levels is vital for enzymatic activities in biological organisms. Hence, knowing how to calculate pH, especially for strong bases, is a fundamental skill in scientific studies.